package cn.yunhe.dplayerdemo3.websocket;

import cn.yunhe.dplayerdemo3.util.ServerEncode;
import org.springframework.stereotype.Component;

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

@Component
@ServerEndpoint(value = "/websocket", encoders = {ServerEncode.class})
public class WebSocket {

    //concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话，可以使用Map来存放，其中Key可以为用户标识
    private static CopyOnWriteArraySet<WebSocket> webSocketSet = new CopyOnWriteArraySet<WebSocket>();
    //这个session不是Httpsession，相当于用户的唯一标识，用它进行与指定用户通讯
    private Session session = null;

    //静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
    private static int onlineCount = 0;

    /**
     * @OnOpen allows us to intercept the creation of a new session.
     * The session class allows us to send data to the user.
     * In the method onOpen, we'll let the user know that the handshake was
     * successful.
     * 建立websocket连接时调用
     */
    @OnOpen
    public void onOpen(Session session) {
        System.out.println("Session " + session.getId() + " has opened a connection");
        try {
            this.session = session;
            webSocketSet.add(this);     //加入set中
            addOnlineCount();
            session.getBasicRemote().sendText("当前人数为:"+getOnlineCount());
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * When a user sends a message to the server, this method will intercept the message
     * and allow us to react to it. For now the message is read as a String.
     * 接收到客户端消息时使用，这个例子里没用
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("Message from " + session.getId() + ": " + message);
    }

    /**
     * The user closes the connection.
     * <p>
     * Note: you can't send messages to the client from this method
     * 关闭连接时调用
     */
    @OnClose
    public void onClose(Session session) {
        webSocketSet.remove(this);  //从set中删除
        subOnlineCount();
        System.out.println("有一链接关闭当前人数为： " + session.getId() + " has closed!");
    }

    /**
     * 注意: OnError() 只能出现一次.   其中的参数都是可选的。
     *
     * @param session
     * @param t
     */
    @OnError
    public void onError(Session session, Throwable t) {
        t.printStackTrace();
    }

    /**
     * 这个方法与上面几个方法不一样。没有用注解，是根据自己需要添加的方法。
     *
     * @throws IOException 发送自定义信号，“1”表示告诉前台，数据库发生改变了，需要刷新
     */
    public void sendMessage(Object o) throws IOException {
        //群发消息
        for (WebSocket item : webSocketSet) {
            try {
                item.session.getBasicRemote().sendObject(o);
            } catch (IOException e) {
                e.printStackTrace();
                continue;
            } catch (EncodeException e) {
                e.printStackTrace();
            }
        }
    }

    public static synchronized int getOnlineCount() {
        return onlineCount;
    }

    public static synchronized void addOnlineCount() {
        WebSocket.onlineCount++;
    }

    public static synchronized void subOnlineCount() {
        WebSocket.onlineCount--;
    }
}
